The invention relates to methods and equipment for synchronizing a database between two parties via a mobile network. In a very common but non-restricting application, one party is a desktop computer, while the other one is a portable computer, a pocket computer or a “smart” telephone. The database contains data items, such as documents, calendar events, meeting requests, address book entries or the like that can be changed at either party. As commonly used in the context of databases, synchronization means reducing or eliminating differences between the database copies maintained at the parties, which are supposedly similar but at least one database contains changed data items which are not reflected in the other database.
Prior art database synchronization techniques via a mobile network are developed for a circuit-switched networks, or they attempt to simulate circuit-switched operation by means of sessions. In a session-based database synchronization, a session is established between the two parties, differences between the database copies are detected and eliminated by transmitting differing data items between the parties, after which the session is closed. In many mobile applications, database synchronization between a mobile terminal and an office computer takes place when the mobile terminal is inserted in a cradle that, in addition to the database synchronization, may load the mobile terminal's battery.
Such prior art database synchronization techniques are suitable for applications that are not time-critical, i.e., applications that tolerate long periods of time between synchronization sessions. If session-based synchronization techniques are used for time-critical databases that have to be synchronized frequently, a major problem is the signalling overhead caused by the session establishment. In time-critical applications, a synchronization session is frequently established merely for detecting potential differences between the database copies, and if no differences are detected, the session is closed without actually transferring any data items between the parties. The overhead is a particular problem in mobile applications in which data transfer is expensive, even if it is only overhead data. Any superfluous traffic also loads the mobile terminal's battery.